Robustness of the van Hove scenario for high-Tc superconductors

The pinning of the Fermi level to the van Hove singularity and the formation of flat bands in the two-dimensional t-t' Hubbard model is investigated by the renormalization group technique. The "van-Hove" scenario of non-Fermi-liquid behavior for high-Tc compounds can take place in a broad enough range of the hole concentrations. The results are in qualitative agreement with the recent ARPES data on La2CuO4.Comment: 4 pages, LaTeX, 3 figure

Stripes, Vibrations and Superconductivity

We propose a model of a spatially modulated collective charge state of superconducting cuprates. The regions of higher carrier density (stripes) are described in terms of Luttinger liquids and the regions of lower density as a two-dimensional interacting bosonic gas of d_{x^2-y^2} hole pairs. The interactions among the elementary excitations are repulsive and the transition to the superconducting state is driven by decay processes. Vibrations of the CCS and the lattice, although not participating directly in the binding mechanism, are fundamental for superconductivity. The superfluid density and the lattice have a strong tendency to modulation implying a still unobserved dimerized stripe phase in cuprates. The phase diagram of the model has a crossover from 1D to 2D behavior and a pseudogap region where the amplitude of the order parameters are finite but phase coherence is not established. We discuss the nature of the spin fluctuations and the unusual isotope effect within the model.Comment: 51 pages, 20 figures. Post-March Meeting version: New references are added, some of the typos are corrected, and a few new discussions are include

Video frame size modeling for User-Generated traffic in an Enterprise-Like environment

Smart mobile devices have displaced personal computers in many daily applications such as internet browsing and email. However, for content creation, users still need to use a large display, keyboard and mouse. Many initiatives are currently working on enabling I/O functionality for content creation and peripheral access, and on preserving the grab-and-go experience where the mobile device is not tethered to the docking station but merely placed in proximity of it and the traffic is carried over Wi-Fi. Maintaining the Quality of Service (QoS) and Experience (QoE) of low-latency, high fidelity video (for example the desktop view of a smart device) when transmitted over a Wi-Fi link in heavily loaded environments has been proven problematic. In this work, we propose for the first time in the relevant literature to the best of our knowledge, a highly accurate video traffic model that is capable of predicting the volume of video traffic generated by an average user's computer during a day. Our modeling techniques are tested on real user-generated screen mirroring traffic from a large shared cube space similar to an enterprise environment, and can be easily used as source traffic generators in order to facilitate the study of H.264 transmission performance over wireless networks

Efficient policing for screen mirroring traffic

The greediness of multimedia applications in terms of their bandwidth demands calls for new and efficient network traffic control mechanisms, especially in wireless networks where the bandwidth is limited. In an enterprise-like environment, an additional burden is expected to be added to the network by screen mirroring traffic. Smart mobile devices are displacing personal computers in many daily applications but at the same time users still need to use a large display, keyboard and mouse. Hence, the transmission of low-latency, high fidelity video over a Wi-Fi link can lead to significant unfairness among users in terms of the bandwidth that is available to them, if this wireless video traffic is not accurately policed. In this work, we focus on the problem of policing screen mirroring traffic. We evaluate various classic and new traffic policing mechanisms, and we propose a new mechanism which is shown to clearly outperform all other mechanisms, including the widely used token bucket policer

Cytokeratin-20 immunocytology in voided urine exhibits greater sensitivity and reliability than standard cytology in the diagnosis of transitional cell carcinoma of the bladder

Objectives. To investigate whether immunocytochemical detection of cytokeratin (CK)-20 could serve as a reliable diagnostic marker for transitional cell carcinoma (TCC) of the bladder. Methods. A total of 232 patients were enrolled in the study. Group 1 consisted of 144 patients with histologically confirmed TCC (62 at diagnosis and 82 in follow-up), and group 2 consisted of 88 subjects, including healthy volunteers and individuals with “non-TCC” conditions. Spontaneously voided urine specimens were obtained from each patient and submitted to immunocytologic and standard cytologic examination. Results. CK-20 immunocytology yielded an overall sensitivity of 65.3%, significantly greater than the sensitivity of urine cytology (54.2%, P = 0.013). A more detailed analysis revealed a sensitivity advantage for the former technique in the detection of primary (61.3% versus 51.6%, P = 0.046), recurrent (68.3% versus 56.1%, P = 0.027), Stage pT1 (81.8% versus 59.1%, P = 0.006), grade 2 (76.2% versus 61.9%, P = 0.031), and grade 3 (82.1% versus 67.9%, P = 0.039) tumors. Moreover, CK-20 immunocytochemistry demonstrated greater overall specificity than cytology (90.9% versus 86.4%, respectively), a difference stemming from the subgroup of lithiasis patients (100% versus 66.7%, P = 0.024). In terms of reliability, the positive and negative predictive values of the immunoassay were greater than those calculated for cytology (92.2% versus 86.7% and 61.5% versus 53.5%, respectively). Conclusions. CK-20 immunocytology is more sensitive than standard cytology in the detection of TCC, particularly of Stage pT1, grade 2, and grade 3 tumors. In view of its high overall specificity and predictive accuracy, it is conceivable that the proposed immunoassay may progressively replace conventional cytologic screening in the diagnosis of bladder cancer

Irrigant transport into dental microchannels

The root canal system of a tooth is a complex geometrical entity, consisting not only of the main root canal, but also of accessory and lateral canals. Bacteria can reside up to hundreds of micrometers inside those channels and may be difficult to reach for the antimicrobial agents with which root canals are irrigated during a root canal treatment. A combined numerical and experimental study was performed to assess the penetration rate of a root canal irrigant into the lateral canals and tubules, considering both diffusion and convection. The numerical model was validated experimentally using a fluorescent dye. Convection was studied separately using a Computational Fluid Dynamics model, validated with Particle Imaging Velocimetry experiments. Both diffusion and convection were found to be slow on the timescale of an irrigation procedure. The contribution of convection was limited to two canal diameters from the canal entrance, making diffusion the main irrigant transport mechanism. More than 10 min of fresh irrigant delivery was required to obtain an 86 % concentration of the irrigant at the far end of a tubule, in the ideal case of a straight tubule without reaction taking place. Diffusion was even slower when the concentration at the lateral canal entrance was not kept constant, as in the case of a single delivery, which suggests that frequent irrigant replenishment and/or irrigant activation during a root canal treatment are beneficial. Alternative methods should be considered to improve irrigant penetration into lateral canals and tubules

Evaluation of claspin as a proliferation marker in human cancer and normal tissues

Claspin is a nuclear protein involved in DNA replication and the DNA damage response. Its structural and functional properties suggest that it may represent a potentially useful proliferation marker. To this end, a monoclonal antibody was generated and the expression of claspin was investigated in normal fibroblasts and various cancer cell lines, as well as in tumour and normal tissues from patients with primary epithelial carcinomas. Immunoblotting analysis confirmed the specificity of the antibody, while immunohistochemistry demonstrated its applicability in archival material. In normal cells and tissues, claspin expression was weak, whereas increased levels were observed in cancer cell lines and tumour specimens. Claspin staining correlated strongly with Ki67 staining in both normal (p < 0.001) and tumour tissues (p < 0.001). However, the labelling index (LI) of claspin was consistently lower than that of Ki67, suggesting that claspin expression may be limited to a narrower part of the cell cycle. Co-localization assays with cyclin A and cell synchronization experiments indicated that claspin expression coincides with the S phase. Interestingly, the relative increase of the claspin LI in tumour samples compared with normal tissues was significantly higher (14-fold) than that of the Ki67 LI (five-fold), suggesting that claspin may be a more sensitive marker of aberrant proliferation. Copyright (c) 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd